The present invention relates to core drilling and, more particularly, to an apparatus for extracting cores from drilled holes.
Rotary core drilling involves drilling holes coring the earth using an annular drill bit or head attached to drill machinery which rotates and pushes the drill head downward into the ground. These drills core rock such that, when the drill head is withdrawn, a barrel shaped core material is left within the bore hole, as the drill head just cut along a periphery thereof. This core material is awkward and cumbersome to remove, particularly in the case of wide diameter cores.
Current apparatus and methods for grabbing and withdrawing the cores often take several hours and are expensive. For example, chains or cables can slip off when lifting cores, causing the core to drop back in the hole. Suction methods are time consuming and unreliable, as they require creating a thick drilling mud to suction the core into the drill. Which can be additional problematic because using the drill to extract the core risks damage to the drill itself.
As can be seen, there is a need for an apparatus and method for extracting cores from drilled holes without using the drill itself. Specifically, an apparatus that provides peripheral fingers having wedges so that after the apparatus is lowered into the hole, raising the apparatus therefrom automatically securely grabs and thereby extracts the core, eliminating the chance of dropping the core back into the hole. Furthermore, utilizing a method that does not require the use of the drill further eliminates the possibility of damage to the drill and resulting delays to the project.